Why do copper, gold and cesium have special colors?

Because metals have free electrons, so they have almost continuous energy states going up and down different energy levels and repeating themselves, most metals are silver-white, right?

But why do gold, copper, and cesium have special colors?
I wanted to know more about this, so I studied the concept of obituary contraction.
I know up to the fact that by orbital contraction, s orbtal is contracted by applying a relativity effect.

To conclude, I wonder why gold and copper cesium have special colors.
I want you to explain in detail and in detail.

I've turned the translator. It may not match the terms you use. Please consider this.

Einstein's elucidation of the quantum spacing of electrons and photons emitted from changes in the quantum spacing of electrons in atomic orbitals, vis a vis the emission and absorption spectra of photons, offers a clue why certain elements or compounds emit light in the 590nm range (that "orange" metal effect) or any other visible wavelength.

Einstein's elucidation of the quantum spacing of electrons and photons emitted from changes in the quantum spacing of electrons in atomic orbitals, vis a vis the emission and absorption spectra of photons, offers a clue why certain elements or compounds emit light in the 590nm range (that "orange" metal effect) or any other visible wavelength.

My understanding is that the colours correspond with the plasmon resonance frequencies, which involve free electrons, rather than the orbital effects you mention.

I am not going to try to answer why the bulk metals have the colour because I don't specifically know, but I assume it is because of where the atomic orbital energies lie. However, in my opinion it has nothing to do with relativistic effects on the 1s orbitals. I have no doubt there are such relativistic effects on the 1s electrons, but they do not affect then outer levels, and it is changes between such outer levels that give colours. In my opinion, the outer wave functions are not equivalent to the excited states of hydrogen, and they are actually of significantly lower energy because they can form superpositions including waves that would otherwise not be permitted by the Exclusion Principle. The evidence is in I. J. Miller 1987. The quantization of the screening constant. Aust. J. Phys. 40 : 329 -346. You can see it and judge for yourself. It is not a complete explanation because there is clearly some additional rather minor effects, which probably are screenings defects, and some slightly larger deviations that depend on whether n is odd or even, and are greater as ℓ increases. My interpretation of what is going on is in my ebook "Guidance Waves", but whether you accept that or not is beside the point as the correlations in the cited paper stand independently of what causes them. If you accept those, no relativistic effects are required, and you may notice that thallium and lead are well-behaved, but their inner s electrons will be in greater electric fields than gold.

In the initial question Saeho wrote:
"I know up to the fact that by orbital contraction, s orbtal is contracted by applying a relativity effect."
This explanation is quite common in chemistry textbooks and some papers. I was merely offering Saeho this explanation.

Within the free electron gas model (Drude model) the reflectivity of a specific metal depends only on the plasma frequency and the relaxation time. The free electron gas model predicts a relatively structureless reflectivity, viz. it cannot account for characteristic thresholds that appear in the frequency dependent reflectivities of real metals. Nevertheless, the free electron gas model allows to qualitatively understand an essential feature of all metals, namely the high reflectivities.

Deviations from the predictions of the Drude model, i.e., significant structures in the reflectivity curves of real metals, are related to interband transitions which are not taken into account by the free electron gas model. The characteristic shiny colorus of various metals can be attributed to such interband transitions.

Dear Vanadium 50. The reason I originally brought it up is because the original questioner said, "I know …." I wished to point out that maybe "know" was premature. The rest of the times I mentioned it was in response to people questioning my original post. It is actually a widespread belief, e.g. Pyykö, P. 2012. The physics behind chemistry and the periodic table. Chem Rev. 112: 371 – 384.

Dear Vanadium 50. The reason I originally brought it up is because the original questioner said, "I know …." I wished to point out that maybe "know" was premature. The rest of the times I mentioned it was in response to people questioning my original post. It is actually a widespread belief, e.g. Pyykö, P. 2012. The physics behind chemistry and the periodic table. Chem Rev. 112: 371 – 384.

I agree, many people that I have asked this question either didn't know (most common) or believed it was the relativistic effect of electrons in the 1s orbital.